8 Most Common Power Quality Problems

Unbalanced Voltage - Most industrial electrical loads are designed for 3 phases of current at either 480 volts or 600 volts. A 600 volt motor is optimized when it receives 3 phases of current at 600 volts. Often, electrical systems can become destabilized and each phase will deliver current at a different voltage such as 570, 580 and 590 volts respectively. Even minor imbalances can generate heat and electrical losses.

Voltage Fluctuations - Voltage may also fluctuate within a single phase. Depending on the loads, the phase can be measured within a range with a maximum, a minimum and average voltage. Motors and equipment are designed to be most efficient at a set voltage and any minor fluctuations, up or down, will decrease the motor’s efficiency, generate heat and electrical losses. Significant voltage fluctuations can cause equipment to shut down or fail.

Unbalanced Current - Imbalanced loads can cause phase currents, thus creating negative voltage sequences and circulating currents. This can result in higher equipment failures and maintenance costs. Additionally, imbalanced loads may generate higher demand charges from the utility if the utility is billing demand on the highest phase.

Power Factor - In alternating current (AC) systems with inductive loads, (i.e. motors) the current wave form often lags the voltage wave form. The greater the variance, the lower the power factor, the more energy wasted. Additionally, many utilities apply a power factor penalty to electric bills if power factor drops below a pre-determined efficiency.

Harmonics - Most AC electrical equipment in North America is designed for AC electricity at 60 Hz or alternating cycles per minute. Any electrical current above 60Hz is called a harmonic. Harmonics are not only wasted power but can also damage equipment.

Surges & Transients - A transient is a very short increase or decrease over nominal voltage and a surge is an increase with a longer duration. Electrical surges and transients can significantly damage plant equipment and trip protective devices.

Brownouts - A brownout is a temporary voltage decrease from the supply. Brownouts can damage equipment and can also shut down operations.

Intermittent Supply Failure - An intermittent supply failure is a temporary loss of voltage. These types of failures can shut down entire facilities and cause production malfunctions.

KVA Reductions as high as 20%+ & KW reductions from 3% to 6%